Method of protecting metal surfaces against abrasive wear in submersible pumps

ABSTRACT

SOLUTIONS OF WATER SOLUBLE AND/OR DISPERSIBLE OXYALKYLATED QUATERNARY FATTY AMINES NOT ONLY OFFER PROTECTION AGAINST ABRASIVE WEAR TO SUBMERGED METAL SURFACES, SUCH AS IN SUBMERSIBLE OIL WELL PUMPS, BUT ALSO THROUGH THEIR ANTI-BACTERIAL AND CORROSION INHIBITING ACTION OFFER PROTECTION AGAINST CORROSION AND BACTERIAL DETERIORATION OF THE PUMP.

United States Tatent O ABSTRACT OF THE DISCLOSURE Solutions of watersoluble and/or dispersible oxyalkylatedquaternary fatty amines not onlyoffer protec- "tion' against abrasive wear to submerged metal surfaces,such as in submersible oil Well pumps, but also through theiranti-bacterial and corrosion inhibiting action olfer protection againstcorrosion and bacterial deterioration of the pump.

Inrecent years hydraulic pumping systems for oil wells havelgone intowidespread commercial use. These systerns utilize subsurface pumps whichare positioned within the .oil well casing near the production stratum.The moving parts of these pumps operate with very close tolerances,and'the problem of abrasive wear is severe, especially when a brine orsaline solution is employed. lirines are not ordinarily usable ashydraulic fluids because of their corrosive nature.

Chemical agents for use in lubricating submersible oil well pumps shouldbe water-soluble or dispersible so that they can be introduced into theaqueous hydraulic fluid at the surface of the well, and the chemicalagent must be adsorbed on the metal surfaces to be lubricated as thehydraulic fluid circulates over these surfaces. The chemical agent,after adsorption on the metal surfaces must function as a highlyeffective lubricant, that is, it 'must reduce abrasive wear between thesurfaces. The

lubricant should also have the property of remaining on the metalsurfaces under a high applied pressure or torque, as would be generatedbetween the relative moving metal surfaces of the pumps. In other words,the lubricant should have good boundary properties to minimize wear andto prevent any increase in the tolerances of the contacting parts, andit should also be effective as an extreme pressure lubricant so that itis not squeezed off of the surfaces or desorbed at torques of greaterthan 60 to 80 inch-pounds.

Inoil production there exists a great number of solutes which" are verycorrosive to the submerged pumps, for example, salts such as NaCl, CaClBaCl sulfates of such rnetals'and gases, such as H 5, which are verycorrosive to the metals commonly used in oil, water and gas "production.In addition to corrosion, damage is also caused by bacteria, such assulfate reducing bacteria, which attack the metal surface of the pumpsand in so doing produces colonies of bacteria (black slime) and hydrogensulfide, which is the product of the bacteria, atscram the metalsurface. Both bacterial attack and H 8 destroy the metal. Thus an idealsubsurface pump lubricant, or more properly stated a pump protectant, isone that not only lubricates the metal parts but also protects againstcorrosion including that resulting from bacterial attack on the metalconstruction of the pump. Formulations lwhich afford both lubricatingand anti-bacterial action are ordinarily achieved by using individualingredients each of which does a particular job. However, the use of asole agent which would perform both functions would have a definiteadvantage over formulations containing multiple components.

. Ihave now discovered that solutions of water soluble and/ordispersible oxyalkylated quaternary fatty amines 3,661,784 Patented May9, 1972 ICC not only offer protection to submerged metal surfaces, suchas in submersible oil well pumps, against abrasive wear but also offer,through their anti-bacterial and corrosion inhibiting action, protectionagainst deterioration of the pump due to corrosion and bacterial action.

The compositions employed in this invention are oxyalkylated quaternaryfatty amines capable of being dissolved and/or dispersed in an aqueousmedium. They may be represented by the following general formularepresents the quaternary ammonium group, R represents substituted groupcomprising the quaternary ammonium substitution which are preferablyhydrocarbon such as alkyl, aryl, cycloalkyl, alkenyl, etc., butpreferably alkyl; OA represents the oxyalkyl group such as derived fromethylene oxide, propylene oxide, butylene oxide, etc., as homo, hetero,block, etc. units: the sum of a+b=4 so as to make up the substitutionunits necessary for a quaternary group, Z comprises an optional groupwhich is employed to end cap the oxyalkylation group such as an acylgroup, a fractional acyl group having unreacted carboxyl group, i.e.

ether group, sulfonate, sulfate, etc., groups, salts thereof, etc.

Polyquaternaries, such as d-i-, tri-, etc. quaternaries can also beemployed for example of the general formula where 0 0 f). F (T); m 1x zz lb L-Jh m where a+b-=3, m is an integer l, 2, 3, etc., B is a linkinggroup such as alkylene, alkylene-o-alkylene, alkarylalkyl, etc., i.e. ahydrocarbon group, a hydrocarbon group containing other elements, etc.

Typical examples include the following:

69 mmomnnx e amuoanmtx o 0 G3 amuoAnii-niion x 6 RN omnd-n-dornax eaammo A ,,so,11 x

9 e RN[(OA)nSOaH]2X etc.

The following illustrates where R is other than hydrocarbon such as 9IEIO( i!CHgbP-(OA) 11X and salts thereof where the N-carboxylate unit isderived from chloracetic acid. Other chloracids can also be employed.

Polyquaternary may be illustrated as follows:

Y=Alkylene, aryl, alkarylalkylene, alkylene-O-alkylene, etc.

These diquaternaries can also be acylated, etherified, 4O sulfated,sulfonates, etc. and salts formed therefrom in the manner of themonoamines.

All of the above quaternaries may have any suitable anion X which may behalides, sulfates, carboxylates, etc., but preferably chlorides.

The n value of alkylene oxides added in the above formulas may varywidely depending on the particular compound, the system in which it isemployed, etc., such as from 1-100 or more, such as from 1-50, forexample from 1-25, but preferably 1-10, with optimum results of from3-5.

The R groups may have 1-30 or more carbons and preferably have at least1 fatty group, i.e. 7-30, but preferably 12-18 carbons and also at least1 lower alkyl such as methyl group.

A preferred group of compounds has general formula h-W R-N x u-10H whereR has 12-18 carbon atoms and X is an anion which may be halides,sulfates, carboxylates, etc., but preferably chlorides.

where R R R and R are selected from the group consisting of hydrogen, analiphatic, cycloaliphatic, aryl, etc., group for example ethylene oxide,propylene oxide, butylene oxide, amylene oxide, octylene oxide, styreneoxide,

4 methyl-styrene oxide, cyclohexene oxide (where R and R are joined tomake a ring), etc.

Equivalents of alkylene oxides can also be employed, for examplealkylene carbonates, i.e., ethylene carbonate, propylene carbonate,butylene carbonate, etc. In addition, alkylene oxides of the glycide,methyl glycide type can also be employed.

Commercially available quaternary compounds are limited by theirsolubility in any given solvent thus requiring the use of varioussolubilizers and/or wetting agents or surfactants to overcome thisdeficiency. However, such use often detracts from the function of thequaternary group as to surface bonding, surfactancy and/or bactericidalaction. However, by oxyalkylating the quaternary compound itself, thecompound has the desired modification built into the molecule itselfrather than being exteriorly modified by mixture with another distinctand separate compound.

By the proper addition of the proper type and amount of alkylene oxides,the water solubility and/or dispersibility can be increased ordecreased. For example, by employing a hydrophilic alkylene oxide, suchas ethylene oxide, water solubility and/or dispersibility can beincreased. By employing a hydrophobic alkylene oxide, ie other thanethylene oxide, such as propylene oxide, butylene oxide, etc., the watersolubility and/or dispersibility can be decreased. In general, it isdesirable to add no more alkylene oxide than is necessary to obtain thedesired properties. Stated another way, the quaternary compound shouldbe modified to achieve the desired balance of lubricity, bactericidalaction, surfactancy and corrosion inhibition properties.

The following compound which gave the proper bal ance of lubricity,corrosion inhibiton, and bactericidal action is employed to illustratethe present invention.

Example A HzcHzo) XH RN 01 (CHzCH20) II Ex. B: Ex. C:

Cocoamine Tallowamine (C Ex. D: Hydrogenated tallowamine Ex. E:Hexadecylamine They all exhibit the properties of lubricity, corrosioninhibition and antibacterial action, particularly against sulfurreducing bacteria.

USE EXAMPLES In practicing the method of this invention, the lubricatingcompound is dissolved or dispersed in water or in a saline brine, ormore generally in the aqueous phase of a fluid medium, which may consistof an oil and brine mixture, or a pumpable drilling mud having anaqueous phase, etc. The concentration of the lubricating agent in thewater or the aqueous phase of the fluid medium should be sufficient toprovide for the coating of the metal surfaces to be protected againstabrasive wear. Usually, the water of aqueous phase should contain atleast 50 ppm. (parts per million) of the lubricating compound, and inmost applications, it will usually be preferable to employ at least ppm.of the lubricating compound. Usually, it will not be necessary ordesirable to use concentrations greater than 500 to 1000 ppm. For use inoil well subsurface pumps where the lubricating compound is introducedinto the brine employed as the hydraulic fluid, concentrations of from50 to 500 p.p.m. 'are satisfactory. For example, good results have beenobtained in such applications with concentrations ranging from 100 to200 p.p.m. The aqueous phase containing the lubricating compound iscontacted with, or preferably circulated over, the metal surface to beprotected against abrasion. If desired, the surface may be continuallytreated with the water or aqueous phase containing the lubricatingcompound, thereby tending to maintain the desired protective layer orfilm of the lubricating compound during operation of the pump or similarapparatus.

The method of this invention is further illustrated by its applicationto the lubrication of subsurface hydraulic pumps in oil Well productionoperations. The oxyalkylated quaternary ammonium compound is employed asa lubricant in the aqueous power fluid at a concentration of from 150 to200 p.p.m. The power fluid may be salt water or fresh water. Beforecirculation to the subsurface pump, the power fluid will be kept in oneor more surface tanks, and is therefore convenient to introduce thelubricating agent into the fluid while it is under surface storage. Fora so-called open system the fluid will only be circulated once, andtherefore it is a simple matter to achieve the desired concentrationintroducing the lubricating agent into the fluid before it iscirculated. For a closed system where the aqueous hydraulic fluid isrecirculated after it has been separated from the oil, there may be someresidual lubricating agent in the fluid, and it may be desirable to addonly sufficient lubricating agent to make up the concentration to thedesired level before the fluid is recirculated. Alternatively, a higherthan necessary concentration can be employed for the initialcirculation, such as a concentration of 500 to 600 p.p.m., and the fluidcan be recirculated until the concentration drops below the desiredlevel for maximum lubricating protection. With this procedure, make-uplubricating agent need only be added periodically. If desired, anauxiliary corrosion inhibitor can also be incorporated in thecirculating fluid. The procedure just described is applicable to variouscommercial subsurface pumps, such as those supplied by the Fluid PackedPump (10., a division of the National Supply Company, or by Kobe, Inc.

While in the foregoing specification this invention has been describedin relation to certain preferred embodiments thereof and many detailshave been set forth for the purpose of illustration, it will be apparentto those skilled in the art that the invention is susceptible to otherapplications and embodiments and that many of the details describedherein can be varied considerably without departing from the basicprinciples of the invention.

Having thus described my invention what I claim as new and desire toobtain by Letters Patent is:

1. The process of simultaneously lubricating and protecting subsurfacemetal surfaces in abrasive wear contact against corrosion andbactericidal action characterized by adding an oxyalkylated quaternaryamine salt to water or a saline brine, said amine salt being Eto),H Raf(EtO) H where R is alkyl or alkenyl of 12-18 carbon atoms, x is 1-10, yis 1-10 and X is a halide.

2. The process of claim 1 Where R is stearyl, the sum of x and y isabout 3 and X is chloride.

3. The process of claim 1 where R is tallow, the sum of x and y is about3 and X is chloride.

References Cited UNITED STATES PATENTS 2,738,325 3/1956 Rydell 252-8.55D

2,344,886 3/1944 Lieber 252-34 X 2,759,975 8/1956 ChiddiX et a1 25234 XFOREIGN PATENTS 261,036 11/1963 Austrialia 252390 DANIEL E. WYMAN,Primary Examiner W. J. SHINE, Assistant Examiner US. Cl. XJR.

